Preparation of ammonium polythiomolybdate

ABSTRACT

A novel composition of matter, ammonium polythiomolybdate, having the empirical formula 3MoS4.2NH4OH.

United States Patent 1191 Kurtak et a1.

[ Oct. 9, 1973 PREPARATION OF AMMONIUM POLYTHIOMOLYBDATE [75] Inventors: Charles R. Kurtak, Bishop, Califi;

Laurence D. Hartzog, Kearney, Ariz.

[73] Assignee: Union Carbide Corporation, New

York, N.Y.

22 Filed: Dec. 7, 1970 21 App1.No.:95,990

52 us. c1 423/56, 423/55, 75/103, 75/108, 423/517 511 int. c1. C01g 39/00, c2215 49/00, c2215 3/00 6/1959 Spengleret a1. 23/15 W UX 3/l965 Kurtak 23/15 W X OTHER PUBLICATIONS Gmelin, I-Iandbuch Der Anorganischen Chemie, 8th Edition, 1935, System No. 53, Pages 267-269.

Primary Examiner-M. Weissman Attorney-Paul A. Rose, Harrie M. Humphreys and Frederick J. McCarthy, Jr.

[ 5 7] ABSTRACT A novel composition of matter, ammonium polythiomolybdate, having the empirical formula 3M0S4.2N- H OH.

1 Claim, No Drawings PREPARATION OF AMMONIUM POLYTHIOMOLYBDATE This invention relates to the preparation of a molybdenum compound having the empirical formula 3MoS '2Nl-l Ol-l and designated as ammonium polythiomolybdate.

It is an object of the present invention to provide a novel compound of molybdenum.

It is a further object of the present invention to provide a method for preparing ammonium polythiomolybdate.

Other objects of the present invention will be apparent from the following description and claims.

The novel compound, ammonium polythiomolybdate, 3MoS -2NH Ol-l, can be prepared by a process which comprises reacting in an ammoniacal aqueous environment, ammonium molybdate, ammonium sulfide, and elemental sulfur. The reaction is conducted under pressure at elevated temperatures.

A novel process for producing ammonium polythiomolybdate, 3MoS '2NH Ol-l, comprises heating under pressure an aqueous ammoniacal solution of ammonium molybdate and ammonium polysulfide (elemental sulfur dissolved in ammonium sulfide) to cause reaction therebetween and the production of a dark red crystalline precipitate. Suitable reaction temperatures are in the range of about 175 to 220C and suitable pressures are from about 300 psig to 700 psig.

The above process corresponds to the following equation:

The aforedescribed process can be practiced by providing an ammoniacal ammonium molybdate solution by dissolving molybdic oxide, molybdic acid or other ammonium molybdate salts, e.g., ammonium para molybdate and tetramolybdate in sufficient ammonium hydroxide, either at ambient or elevated temperatures and pressures to obtain a solution with a pH of at least about 9.0.

To the aforedescribed solution is added ammonium polysulfide, i.e. ammonium sulfide in which elemental sulfur is dissolved, and this reaction mixture is heated in an autoclave to a temperature in the range of 175 to 220C and maintained in this temperature range, under pressures of from 350 psig to 700 psig for from about 1 to 2 hours, whereby a precipitate of dark,

blood-red crystalline material is obtained. This material, ammonium polythiomolybdate 3MoS -2NH OH, is insoluble in cold water or aqueous ammonia and acetone, but is soluble in hot water or aqueous ammonia (80C) and produces therein an orange colored solution.

Upon heating in air at 500C, ammonium polythiomolybdate is oxidized to M With heating in an atmosphere of hydrogen at 390C, ammonium polythi-.

TABLE monoclinic Empirical Formula Infrared absorption maxima Specific gravity Crystalline Structure n'y= 2.3; na= 2.2 (negative sign of elongation) diamagnetic lndices of refraction Magnetic moment EXAMPLE I Fifty grams of molybdenum (as molybdic oxide) were dissolved in 500 ml of 3 Molar NH OH. The molybdic oxide employed was contaminated with tungsten and the ratio of Mo to W0 in the resulting solution was approximately 3:1. Added to this solution were 425 ml of 42 percent ammonium sulfide solution in which had been dissolved 46 grams of flowers of sulfur.

The foregoing reaction mixture was digested in an autoclave at 198C for 2 hours. The pressure developed in the autoclave was 350 psig. A dark, blood-red crystalline precipitate was obtained which was analyzed and found to be ammonium polythiomolybdate,

3MoS 2NH Ol-l. The yield of molybdenum was 96.5

percent based on the amount ofmolybdenum employed. The precipitated material was in the form of six-sided prisms (pseudohexagonal) with jagged bases averaging 100 microns in length with average diameters of 15 microns.

When this material was roasted in air and converted to Moo the oxide product was found to have a Mo to W0 ratio of 8,300:l.

Thus, the production of ammonium polythiomolybdate in accordance with the present invention, provides a highly selective precipitation of molybdenum from a tungsten contaminated solution.

A further example is provided to illustrate a novel method of producing M08 from ammonium polythiomolybdate.

EXAMPLE 1] Ten grams of ammonium polythiomolybdate were heated in a tube furnace at 600C under a hydrogen atmosphere for 2 hours.

The resulting product, when analyzed, shows the stoichiometry of M08 Surface area measurement showed 20 square meters per gram.

As shown by Example II, the novel material of the present invention can be used in the production of MOS, which material is useful as a lubricant and catalyst.

What is claimed is:

1. A method for recovering molybdenum from tungsten-contaminated molybdenum oxide which comprises dissolving the tungsten-contaminated molybdenum oxide in an aqueous ammoniacal media together with ammonium sulfide and elemental sulfur to provide a solution having a pH of at least about 9 and subjecting said solution to an elevated temperature in the range of about l to 220C and pressure conditions of about 300 psig to 700 psig for a time sufficient to thereby precipitate the molybdenum values in the form of a dark red crystalline material which is essentially free of tungsten and which has the following properties Magnetic moment 

